1. Field of the Invention.
This invention relates to missiles and, particularly, to an apparatus that insures that lateral support pads positioned between the missile and a canister that holds the missile before launching are separated in a controlled manner after launch.
2. Description of the Prior Art.
In general, canister launched missiles are ejected from the canister by expanding gases from a gas generator. The expanding gases push against a sabot-seal device positioned near the nozzle of the missile. The sabot-seal forms a gas tight seal between itself and the canister and further acts as a centering means of the missile within the canister. After a given interval of time from the firing of the gas generator, a firing signal ignites the missile motor. During ejection of the missile from the canister, supporting means insures that the missile and the canister do not damage either.
In particular, supporting means presently used in the MX system uses a plurality of lateral support pads around the missile which center and support the missile in the canister. The support pads are detachably held in place by releasing means until the firing signal releases the plurality of support pads. The support pads are arranged in annular sets having no connection between each set. Each set is held in place by the releasing means. Because the sets are not interconnected, it is likely that the support pads will recontact the missile skin or nozzle. The likelihood of this occurring increases greatly in windy launch conditions or when the missile is launched at an angle from the vertical.
Another method consists of canister mounted support pads deposed in a plurality of annular rings about the inside surface of the canister. Each annular set of pads has a lip seal which forms a gas seal between the pads and the missile surface. The sabot-seal as noted in the first method is not required since the pads form a seal and align the missile. One disadvantage is that a cold gas or steam eject launch is required since the first stage engine is exposed to the gas generator flow. Another disadvantage is that the stresses developed at the lip seals are unacceptable because they are cumulative.
Another method is a gas bearing approach using part of the gas generating efflux to drive orifices mounted in the canister surface surrounding the missile. The sabot-seal is still used in this method. Because of having the orifices in the walls and the high pressure gas therein, the canister has to have a strong wall structure. This further complicates the manufacturing of the canister as presently accomplished.
A still further method is a pad capture technique where the pads are picked off the missile as it exits the canister. This requires that the mechanism be deployed prior to launch and entails additional hardware to the presently existing canister.